Weekend Homework- Nervous System

Crash Course- The Nervous System
https://www.youtube.com/watch?v=x4PPZCLnVkA

Here is the main page for the Khan videos on the nervous system:
https://www.khanacademy.org/science/biology/human-biology/neuron-nervous-system/v/anatomy-of-a-neuron

The questions will be posted in batches- the first batch Saturday morning and the second batch Sunday morning.

Video #1- “Anatomy of a Neuron”

1. What is the function of the neuron?
2. Draw and label a typical neuron.
3. Describe the various parts of the neuron (soma, dendrite, axon, axon terminal, axon hillock, Schwann cells (myelin sheath), and nodes of Ranvier)
4. How do neurons connect to each other?

Video #2 and #3- "The Sodium Potassium Pump" and "Correction to Na-K Pump Video"

1. What is an action potential?
2. What is a voltage potential?  Or, what is voltage in general?  What is the difference between the outside and inside of the neuron in MV?
3. What is the role of sodium-potassium pumps?  Where are they located?  How do they get the energy to “pump?”
4. What does ATP-ase do?  Why does the Na-K pump need to use energy from ATP?
5. How many and what kinds of ions are pumped in each “pump?” Where are they pumped?  So, how does Khan use this to explain why there is a voltage potential across the membrane?  How does he correct himself in the third video? (In other words, what is the main reason for the voltage potential?)
6. How is a voltage potential like a concentration gradient?

Video #4- “Electrotonic and Action Potential.” This is one of the most useful Khan videos of all time!!!

1.     Why does sodium flow through the membrane (two reasons)

2.     Describe the spread of an electrotonic potential.

3.     What are voltage-gated ion channels and how do they work?

4.     What is the relationship between the electrotonic potential and the opening and closing of the ion channels?  How is this dynamic responsible for the propagation of the signal?

5.     Define action potential.

Video #5- “Saltatory Conduction in Neurons.”

1.     How is the structure of the neuron related to its function?  ***One of the main questions in the AP Biology curriculum***

2.     How does the stimulus spread from the dendrite to the axon hillock?

3.     What is the threshold voltage that is required to open the voltage-gated sodium channels?  How does this explain how we can be touched, but not feel it?

4.     Does the voltage go up or down when the voltage gated ion channels are triggered?  Does this mean the voltage difference is greater or less?

5.     Why do we insulate wires?  How does this relate to the axon? Why is it not a perfect analogy?  Why can’t we surround the  axon completely with Schwann cells?

6.     What are the pros and cons of electrotonic potentials and action potentials?

7.     Sometimes teachers say that the signal “jumps from node to node?”  Why is that inaccurate?

8.     Define saltatory conduction.